Belgium’s Railways: Temperature Swings Are the Real Threat

When a heatwave swept across Belgium in late June 2026, it did more than break a 50-year temperature record—it exposed a vulnerability in the country’s railway network that engineers are only beginning to fully understand. While the mercury hit 35.1°C in Uccle, surpassing the previous 1976 record of 32.8°C, the real concern for infrastructure managers wasn’t the peak heat itself. It was what came next.

As De Morgen reported, the most damaging factor for railway infrastructure is not sustained high temperatures, but rapid temperature swings—when the thermometer plunges from 35°C one day to 25°C the next.

The Physics of a Stressed Railway

Steel rails are installed at a specific “stress-free temperature,” typically around 25°C in temperate climates like Belgium’s. When temperatures deviate significantly from this baseline, thermal stress builds up. Rapid changes create uneven stress distribution, and the repeated expansion and contraction cycle accelerates metal fatigue.

“The biggest problem is temperature fluctuations, for example when it goes from 35 degrees to 25 degrees from one day to the next,” Thomas Baeken, spokesperson for Belgian rail infrastructure manager Infrabel, told De Morgen.

The June heatwave caused a doubling of technical incidents on the Belgian rail network, according to Infrabel, though the company emphasized that disruption remained within expectations. Heat-related damage was identified at more than 20 locations across the network, causing track deformation.

Cascading Failures

Heat affects railways in multiple ways beyond track buckling. Overhead power lines (catenaries) sag in high temperatures, increasing the risk that they snag on train pantographs and break, halting all traffic. Electronic signaling equipment can malfunction. And many older Belgian trains lack air conditioning entirely.

SNCB/NMBS cancelled approximately 100 trains daily from 24 to 26 June 2026 due to extreme heat, primarily because older rolling stock could not keep passengers cool. On the high-speed line (HSL 1) between Brussels and France, Infrabel imposed speed restrictions from 24-27 June, reducing trains from 300 km/h to 170 km/h between 13:00 and 19:00, adding roughly 12 minutes to journey times.

John Lawrence, Chair of the Railway Technical Network at the UK Institution of Engineering and Technology, explained the engineering nightmare: “Track buckles and dewirements are what really worry engineers. That brings derailment risks, and overhead lines can sag and catch on pantographs, halting train movements or forcing lengthy reroutes.”

A European Challenge

Belgium’s predicament is not unique. Across Europe, railway operators are grappling with the consequences of more frequent extreme weather. In France, SNCF withdrew 10% of Paris region trains to avoid overheating tracks, and a broken power line caused major disruptions at Paris Gare de l’Est. The UK’s Network Rail faced similar challenges during the record July 2022 heatwave.

Eurostar is taking particularly bold action. CEO Gwendoline Cazenave has adapted the company’s €1.9 billion order for 50 new trainsets from Alstom to withstand temperatures up to 55°C—up from the previous 45°C limit—in response to fears of “Saudi-style” summer temperatures in Europe.

The Cost-Benefit Calculus

Adapting Belgium’s entire 3,600 km rail network to withstand more frequent extreme heat would be, in Baeken’s words, “a gigantic measure.” Infrabel is now discussing whether to adjust the standard stress-free temperature for rail installation to account for the new climate reality.

Professor Niels van Oort of TU Delft, an expert in public transport, framed the dilemma clearly: “Now that extreme weather occurs more frequently, the cost-benefit analysis is changing. So you’ll more often benefit from a more robust network. This discussion is now recurring everywhere. Not investing is a saving in the short term, but the chance is high that you’ll pay it back in misery in the long term.”

Solutions on the Table

Engineers are exploring a range of potential solutions. Reflective paint can shave five to ten degrees Celsius off rail temperature, according to Professor Antonios Kanellopoulos of the University of Hertfordshire. Rigid overhead power lines that don’t sag in heat are another option, though expensive. Improved temperature monitoring could enable targeted speed restrictions instead of blanket cancellations.

Belgian bus operator De Lijn already applies stricter heat standards than Germany, requiring all systems to function up to 40°C. Professor Ivan Verhaert of the University of Antwerp suggests that water cooling for traction systems—similar to data center cooling—may become necessary for compact train installations.

What’s Next

As climate change accelerates, the question is no longer whether Belgium’s railways need to adapt, but how quickly and at what cost. The discussion about adjusting fundamental engineering standards—like the stress-free temperature of rails—represents a paradigm shift for temperate-climate railway operations.

For now, Infrabel is proceeding cautiously. “We’re not there yet, since such extreme temperatures are not a continuous problem,” Baeken said. But with each passing heatwave, the calculus shifts—and the case for investment grows stronger.